Post by thread:[PICLIST] [OT] MP3

MP3 is composed of frames, each starts with 12 sequential ones (FFF) followed by a header which tells, among other things, how long the frame is, followed by huffman encoded data. It's legal to have any amount of inter-frame information as long as FFF isn't found. Unless the decoder is totally brain-damaged it will extract the frames itself and you can just pass the MP3 to it verbatim. On Wed, 21 Jun 2000, H.P. de Vries wrote: {Quote hidden}> Date: Wed, 21 Jun 2000 16:02:41 +0200 > From: H.P. de Vries <spam_OUTH.P.d.VriesTakeThisOuTSTUD.TUE.NL> > Reply-To: pic microcontroller discussion list <.....PICLISTKILLspam@spam@MITVMA.MIT.EDU> > To: PICLISTKILLspamMITVMA.MIT.EDU > Subject: [OT] MP3 > > I have a question regarding mp3-file formats. > How is a mp3-file put together? I've searched over the internet for this, > but all I get is the standard pages that explain that it's compressed audio > <duh> > I'm designing a hardware mp3-decoder like mp3ar.com. (very early design...) > How do I know when I've got valid mp3-data (frame) in the file? Some files > have weird text(ascii)-like headers. So I kinda need to know when a valid > frame is reached, so I can send it to the decoder. > > Hans > > (This is probably the worst english I've ever written.. sorry for that..) >

I thought MP3 (and also MPEG videos) compression was somewhat different to others (e.g. WAV, AVI, QuickTime). I notice that it doesn't seem possible to edit either MP3 or MPEG formats, for example. I'd assumed that this had something to do with the CODEC needing the whole file data to be able to decode it. I await to be corrected... Chris -- Dr. Chris Kirtley MD PhD Associate Professor HomeCare Technologies for the 21st Century (Whitaker Foundation) NIDRR Rehabilitation Engineering Research Center on TeleRehabilitation Dept. of Biomedical Engineering, Pangborn 105B Catholic University of America 620 Michigan Ave NE Washington, DC 20064 Tel. 202-319-6247, fax 202-319-4287 Email: .....kirtleyKILLspam.....cua.edu http://engineering.cua.edu/biomedical Clinical Gait Analysis: http://guardian.curtin.edu.au/cga Send subscribe/unsubscribe to EraseMElistprocspam_OUTTakeThisOuTinfo.curtin.edu.au

Well, it can't possibly need the whole file to be able to decode it, as there are also streaming mp3-apps. :-) Hans On Fri, Jun 23, 2000 at 02:10:41PM -0400, Dr. Chris Kirtley wrote: {Quote hidden}> I thought MP3 (and also MPEG videos) compression was somewhat different > to others (e.g. WAV, AVI, QuickTime). I notice that it doesn't seem > possible to edit either MP3 or MPEG formats, for example. I'd assumed > that this had something to do with the CODEC needing the whole file data > to be able to decode it. > > I await to be corrected... > > Chris > -- > Dr. Chris Kirtley MD PhD > Associate Professor > HomeCare Technologies for the 21st Century (Whitaker Foundation) > NIDRR Rehabilitation Engineering Research Center on TeleRehabilitation > Dept. of Biomedical Engineering, Pangborn 105B > Catholic University of America > 620 Michigan Ave NE > Washington, DC 20064 > Tel. 202-319-6247, fax 202-319-4287 > Email: kirtleyspam_OUTcua.edu > http://engineering.cua.edu/biomedical > > Clinical Gait Analysis: http://guardian.curtin.edu.au/cga > Send subscribe/unsubscribe to @spam@listprocKILLspaminfo.curtin.edu.au >

But has anyone ever seen such a thing as an MP3 editor or MPEG to AVI converter? Chris -- Dr. Chris Kirtley MD PhD Associate Professor HomeCare Technologies for the 21st Century (Whitaker Foundation) NIDRR Rehabilitation Engineering Research Center on TeleRehabilitation Dept. of Biomedical Engineering, Pangborn 105B Catholic University of America 620 Michigan Ave NE Washington, DC 20064 Tel. 202-319-6247, fax 202-319-4287 Email: KILLspamkirtleyKILLspamcua.edu http://engineering.cua.edu/biomedical Clinical Gait Analysis: http://guardian.curtin.edu.au/cga Send subscribe/unsubscribe to RemoveMElistprocTakeThisOuTinfo.curtin.edu.au

Actually, I am also looking for one.. I need to be able to convert movies generated by matlab to AVI or RAM, any thing that can be streamed..or is it possible to stream mpeg like the mp3? On Fri, 23 Jun 2000, Dr. Chris Kirtley wrote: {Quote hidden}> But has anyone ever seen such a thing as an MP3 editor or MPEG to AVI > converter? > > Chris > -- > Dr. Chris Kirtley MD PhD > Associate Professor > HomeCare Technologies for the 21st Century (Whitaker Foundation) > NIDRR Rehabilitation Engineering Research Center on TeleRehabilitation > Dept. of Biomedical Engineering, Pangborn 105B > Catholic University of America > 620 Michigan Ave NE > Washington, DC 20064 > Tel. 202-319-6247, fax 202-319-4287 > Email: spamBeGonekirtleyspamBeGonecua.edu > http://engineering.cua.edu/biomedical > > Clinical Gait Analysis: http://guardian.curtin.edu.au/cga > Send subscribe/unsubscribe to TakeThisOuTlistprocEraseMEspam_OUTinfo.curtin.edu.au >

Dear Saeed, Yes - that was my point. I've tried looking for such converters several times. I found some links that seemed to be just what I was looking for, but all of the turned out to be dead. I think there's actually no way to convert MPEG to AVI. I think it's an entirely different form of compression. I'd love someone to tell me I'm wrong - but please don't unless you can point us to the software that does it! Chris -- Dr. Chris Kirtley MD PhD Associate Professor HomeCare Technologies for the 21st Century (Whitaker Foundation) NIDRR Rehabilitation Engineering Research Center on TeleRehabilitation Dept. of Biomedical Engineering, Pangborn 105B Catholic University of America 620 Michigan Ave NE Washington, DC 20064 Tel. 202-319-6247, fax 202-319-4287 Email: RemoveMEkirtleyTakeThisOuTcua.edu http://engineering.cua.edu/biomedical Clinical Gait Analysis: http://guardian.curtin.edu.au/cga Send subscribe/unsubscribe to listprocEraseME.....info.curtin.edu.au

That's true. I hadn't noticed it, but there really are no converters (that I know of) for these formats. Weird actually. I mean, if you can decode it, it means you must be able to re-code it somehow. At least by saving the frames and re-assembling them to another movie-format you'd say. But I still think you don't need the entire file to decode it. Actually, I know that for a fact. Try cutting a random part from the end, and it still can be decoded. All the decoder needs is the header-info (I think) from the beginning of the file. It then keeps decoding until it sees no more valid frames. I'll keep looking for such software though! Hans On Fri, Jun 23, 2000 at 04:43:28PM -0400, Dr. Chris Kirtley wrote: {Quote hidden}> Dear Saeed, > > Yes - that was my point. I've tried looking for such converters several > times. I found some links that seemed to be just what I was looking for, > but all of the turned out to be dead. I think there's actually no way to > convert MPEG to AVI. I think it's an entirely different form of > compression. > > I'd love someone to tell me I'm wrong - but please don't unless you can > point us to the software that does it! >

THe trick is to recognize the frame headers (12 1's in a row) usually FF F3 or something, and cut/paste with a hex editor. Based on the bitrate you know how far into the soundbite you are. Good luck Marius On Fri, 23 Jun 2000, H.P. de Vries wrote: {Quote hidden}> That's true. I hadn't noticed it, but there really are no converters (that I > know of) for these formats. Weird actually. I mean, if you can decode it, > it means you must be able to re-code it somehow. At least by saving the > frames and re-assembling them to another movie-format you'd say. > But I still think you don't need the entire file to decode it. Actually, I > know that for a fact. Try cutting a random part from the end, and it still > can be decoded. All the decoder needs is the header-info (I think) from the > beginning of the file. It then keeps decoding until it sees no more valid > frames. > > I'll keep looking for such software though! > > Hans > > > On Fri, Jun 23, 2000 at 04:43:28PM -0400, Dr. Chris Kirtley wrote: > > Dear Saeed, > > > > Yes - that was my point. I've tried looking for such converters several > > times. I found some links that seemed to be just what I was looking for, > > but all of the turned out to be dead. I think there's actually no way to > > convert MPEG to AVI. I think it's an entirely different form of > > compression. > > > > I'd love someone to tell me I'm wrong - but please don't unless you can > > point us to the software that does it! > > >

First - thanks for e-m display info, very helpful. Particularly like Staver's physical address ----- Original Message ----- From: Saeed Saeed > Actually, I am also looking for one.. I need to be able to convert movies > generated by matlab to AVI or RAM, any thing that can be streamed..or is > it possible to stream mpeg like the mp3? and > But has anyone ever seen such a thing as an MP3 editor or MPEG to AVI > converter? > Chris > -- > Dr. Chris Kirtley MD PhD Slightly off the question, I use Real Producer Basic (free from http://www.real.com) (Thank you Dan Creagan, still using it ! invaluable) to convert captured AVI or MPEG to small .rm files for e-mail. A significant reduction in size is possible (50:1) depending on the degradation you can accept. Also, having a troll around various codec warehouses I notice all kinds of splitters, joiners and editors for the different formats. Many have non-expiring evaluation versions that allow you to do most functions. I haven't a specific site address but they aren't hard to find if you search for a particular codec like MP43 or DIVx in a search engine

PIClisters... I´ve been looking for a MP-3 to wave converter. Does anyone know where can I find it ? Thanks Andre RemoveMEacollingEraseMEEraseMEzaz.com.br {Quote hidden}>-----Mensagem original----- >De: Arthur Brown <RemoveMEartbspam_OUTKILLspamcableinet.co.uk> >Para: RemoveMEPICLISTTakeThisOuTspamMITVMA.MIT.EDU <EraseMEPICLISTspamspamBeGoneMITVMA.MIT.EDU> >Data: Sábado, 24 de Junho de 2000 15:31 >Assunto: Re: [OT] MP3 > > >>Re post to list after mix up on subject line >>But I seen this and.... >> >>Look's like tony's front end for mp3 take a look here >>http://www.mp3toexe.com/ >> >>Regard's to all Art >>RemoveMEartbKILLspamcableinet.co.uk >> >>> {Original Message removed}

VirtualDub can convert MPEGs to AVIs. http://www.geocities.com/virtualdub/ Mike On Fri, 23 Jun 2000, Dr. Chris Kirtley wrote: {Quote hidden}> Dear Saeed, > > Yes - that was my point. I've tried looking for such converters several > times. I found some links that seemed to be just what I was looking for, > but all of the turned out to be dead. I think there's actually no way to > convert MPEG to AVI. I think it's an entirely different form of > compression. > > I'd love someone to tell me I'm wrong - but please don't unless you can > point us to the software that does it! > > Chris > -- > Dr. Chris Kirtley MD PhD > Associate Professor > HomeCare Technologies for the 21st Century (Whitaker Foundation) > NIDRR Rehabilitation Engineering Research Center on TeleRehabilitation > Dept. of Biomedical Engineering, Pangborn 105B > Catholic University of America > 620 Michigan Ave NE > Washington, DC 20064 > Tel. 202-319-6247, fax 202-319-4287 > Email: kirtleySTOPspamspam_OUTcua.edu > http://engineering.cua.edu/biomedical > > Clinical Gait Analysis: http://guardian.curtin.edu.au/cga > Send subscribe/unsubscribe to spamBeGonelistprocSTOPspamEraseMEinfo.curtin.edu.au >

Dear Mike, Just tested VirtualDub and it does, indeed, seem excellent! Thanks very much for telling us about it. It's like finding El Doradao! Chris -- Dr. Chris Kirtley MD PhD Associate Professor HomeCare Technologies for the 21st Century (Whitaker Foundation) NIDRR Rehabilitation Engineering Research Center on TeleRehabilitation Dept. of Biomedical Engineering, Pangborn 105B Catholic University of America 620 Michigan Ave NE Washington, DC 20064 Tel. 202-319-6247, fax 202-319-4287 Email: KILLspamkirtleyspamBeGonecua.edu http://engineering.cua.edu/biomedical Clinical Gait Analysis: http://guardian.curtin.edu.au/cga Send subscribe/unsubscribe to EraseMElistprocEraseMEinfo.curtin.edu.au

> From: "Dr. Chris Kirtley" <@spam@kirtley@spam@spam_OUTCUA.EDU> > But has anyone ever seen such a thing as an MP3 editor or MPEG to AVI > converter? Not as such but I have used the related Musicam Layer2 used in some pro audio devices with editing software produced for for it. I seem to recall someone from the manufacturer saying that the editor needs to uncompress x frames of data on the fly before and after the edit point. Don't remember why but it made sense at the time. In this application the encode/decode was done in DSP on proprietary ISA cards made by Digigram in France. Currently I convert to a linear format to edit and then convert back. It's OK for website sound effects etc. but you do lose quality. .

Soundforge does mp3 editing. -----Original Message----- From: Andy Howard [spamBeGonemusicaKILLspamUKONLINE.CO.UK] Sent: 27 June 2000 16:19 To: .....PICLISTspam_OUTMITVMA.MIT.EDU Subject: Re: [OT] MP3 > From: "Dr. Chris Kirtley" <TakeThisOuTkirtley.....TakeThisOuTCUA.EDU> > But has anyone ever seen such a thing as an MP3 editor or MPEG to AVI > converter? Not as such but I have used the related Musicam Layer2 used in some pro audio devices with editing software produced for for it. I seem to recall someone from the manufacturer saying that the editor needs to uncompress x frames of data on the fly before and after the edit point. Don't remember why but it made sense at the time. In this application the encode/decode was done in DSP on proprietary ISA cards made by Digigram in France. Currently I convert to a linear format to edit and then convert back. It's OK for website sound effects etc. but you do lose quality. .